JP2005286133A - Exposure system, alignment processing method, and mask mounting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure system the throughput of which can be enhanced. <P>SOLUTION: A rough movement stage is fitted to a reference base for demarcating a reference face being a position reference. The moving part of the rough movement stage is moved in a direction in parallel with the reference face. Each of a plurality of inching stages has a holding face for holding a processing object, and can move the holding face in a direction in parallel with the reference face with respect to the moving part of the rough movement stage. A beam source for emitting an energy beam to the processing object held on the holding face of a concerned inching stage is arranged to each inching stage. Further, an alignment sensor for the object for detecting the position of the processing object held on the holding face of the concerned inching stage is arranged to each inching stage. The positional relation between each inching stage and the alignment sensor for the object is unchanged with respect to all the inching stages even when the rough movement stage is moved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exposure apparatus and an alignment processing method, and more particularly to an exposure apparatus and an alignment processing method applicable to proximity exposure. Furthermore, the present invention relates to a method for mounting a mask on the exposure apparatus.

  Patent Document 1 discloses a low energy electron beam lithography (LEEEPL) technique. In LEEPL, exposure is performed by placing a wafer and a mask close to each other and irradiating the wafer with a low energy electron beam through the mask. A finer pattern can be formed as compared with lithography using conventional light.

US Pat. No. 5,831,272

  At present, a prototype of the LEEPL apparatus has been completed, but the processing time per wafer of this prototype is longer than the processing time of the conventional ultraviolet exposure apparatus. Even if the moving speed of the stage is increased to the limit value, it is difficult to increase the throughput to that of the conventional ultraviolet exposure apparatus.

  An object of the present invention is to provide an exposure apparatus and an alignment processing method capable of increasing throughput. Another object of the present invention is to provide a method for mounting a mask on the exposure apparatus.

  According to one aspect of the present invention, a coarse movement stage that is attached to a reference base that defines a reference surface that serves as a reference for a position and moves a movable portion in a direction parallel to the reference surface, and holds a processing object. A holding surface is provided, and a plurality of fine movement stages that can move the holding surface in a direction parallel to the reference surface with respect to the movable portion of the coarse movement stage, and are arranged for each fine movement stage. A beam source for irradiating the processing object held on the holding surface of the fine movement stage with an energy beam and an object arranged for each of the fine movement stages and detecting the position of the processing object held on the holding surface of the corresponding fine movement stage When the movable part of the coarse movement stage is moved, the relative movement between each of the fine movement stages and the corresponding object alignment sensor is detected. Location relationship, all of the fine moving stage is always to be the same for the exposure apparatus is provided for the alignment sensor the object is located.

  According to another aspect of the present invention, (a) a processing object is held on each holding surface of a plurality of fine movement stages attached to a movable portion of a coarse movement stage movable in a direction parallel to a reference surface, (B) using a mask alignment sensor that is arranged for each fine movement stage and moves with the movement of the movable part of the coarse movement stage; Detecting a reference mark arranged for each fine movement stage and moving with the movement of the movable portion of the coarse movement stage, and a corresponding alignment mark on the mask; and (c) the coarse movement stage. Move the movable part and place the corresponding reference mark at the position facing the object alignment sensor arranged for each fine movement stage. Detecting a position of the reference mark, and (d) moving the movable part of the coarse movement stage to move the movable part on the processing object held by the corresponding fine movement stage at a position facing the object alignment sensor. A step of detecting the position of the alignment mark on the object by the alignment sensor for the object, (e) a position detection result in the process b, and a movable part of the coarse movement stage in the process c Each of the masks and the processing object held on the holding surface of the corresponding fine movement stage, based on the movement amount and position detection result of the movement, and the movement amount and position detection result of the movable part of the coarse movement stage in the step d. Obtaining a relative position information of the first position is provided.

  According to still another aspect of the present invention, a processing object is held on each holding surface of a plurality of fine movement stages attached to a movable portion of a coarse movement stage movable in a direction parallel to a reference surface, and the fine movement stage Each mask stage is placed in proximity to the corresponding processing object, the mask is held, and the alignment mark on the corresponding processing object is detected by the object alignment sensor arranged for each fine movement stage. The mask is attached to a mask stage of an exposure apparatus that aligns the mask with a corresponding processing object and exposes the processing object through the mask, and includes: (a) holding each fine movement stage A step of holding the mask on the surface, and (b) an alignment mark on the mask held on the holding surface of the fine movement stage is provided with a corresponding alignment center for the object. A step of moving the movable portion of the coarse movement stage so as to be arranged at a position detected by the step (c), with respect to all the masks held on the holding surface of the fine movement stage, with the alignment sensor for the object, A step of detecting the position of the alignment mark on the mask held on the holding surface of the corresponding fine movement stage; and (d) the detection result of the position of the alignment mark on the mask held on the holding surface of one fine movement stage. And (e) all of the steps of moving the movable portion of the coarse movement stage so that the mask is disposed at a position facing the corresponding mask stage, and holding the mask on the corresponding mask stage. A mask mounting method is provided that includes the step of repeating the step d for the mask.

  Since processing objects held on a plurality of fine movement stages can be processed in parallel, throughput can be increased. Since one coarse movement stage is shared by a plurality of fine movement stages, the number of parts can be reduced and the apparatus can be downsized as compared with the case where a coarse movement stage is also arranged for each fine movement stage.

  FIG. 1 shows a schematic view of an exposure apparatus according to the first embodiment. The lower reference base 1 and the upper reference base 2 fixed thereon constitute a reference base 3 that defines a substantially horizontal reference plane. The main components are loaded into the space between the lower reference base 1 and the upper reference base 2.

  A coarse movement stage 4 is mounted on the lower reference base 1. The coarse movement stage 4 includes a coarse movement mechanism and a movable part (top stage), and the movable part can move in a direction parallel to the reference plane by the coarse movement mechanism. Fine movement stages 5 </ b> A and 5 </ b> B are attached on the movable part of coarse movement stage 4. Each of the fine movement stages 5A and 5B includes a fine movement mechanism and a holding surface (top stage), and the holding surfaces of the fine movement stages 5A and 5B are moved with respect to the movable portion of the coarse movement stage 4 by the fine movement mechanism. They can move independently of each other in a direction parallel to the reference plane. Laser interferometers are arranged corresponding to fine movement stages 5A and 5B. The reference mirror of the laser interferometer is fixed to the mask stages 6A and 6B, and the length measuring mirror is fixed to the holding surfaces of the fine movement stages 5A and 5B. The laser interferometer measures the amount of displacement of the holding surfaces of fine movement stages 5A and 5B with respect to mask stages 6A and 6B. An XYZ orthogonal coordinate system is defined in which the plane parallel to the reference plane is the XY plane and the direction in which fine movement stages 5A and 5B are arranged is the X-axis direction.

  Wafers (processing objects) 13A and 13B are held on the holding surfaces of fine movement stages 5A and 5B, respectively. Alignment marks 14A and 14B are formed on the wafers 13A and 13B, respectively. The fine movement mechanism of fine movement stages 5A and 5B moves wafers 13A and 13B held on the holding surface slightly in the Z-axis direction, displaces them in a rotational direction around an axis parallel to Z-axis, and tilts relative to the reference plane. Can be adjusted.

  Reference masks 8A and 8B are attached to the holding surfaces of fine movement stages 5A and 5B, respectively. The reference masks 8 </ b> A and 8 </ b> B move while maintaining the relative positional relationship between the movable parts of the coarse movement stage 4 as the movable part moves. When the holding surfaces of fine movement stages 5A and 5B are moved, both move independently. The reference masks 8A and 8B are composed of a mark support portion that transmits light and reference marks 9A and 9B formed on the mark support portion. Mask alignment sensors (mask alignment microscopes) 7A and 7B are disposed below the reference masks 8A and 8B, respectively. The mask alignment sensors 7A and 7B are fixed to the holding surfaces of the fine movement stages 5A and 5B, respectively, and move while maintaining the relative positional relationship between the movement parts of the coarse movement stage 4 while moving. When the holding surfaces of fine movement stages 5A and 5B are moved, both move independently.

  Mask stages 6A and 6B, wafer alignment sensors (wafer alignment microscopes) 10A and 10B, and leveling sensors 15A and 15B are attached to the upper reference base 2. The mask stages 6A and 6B hold the masks 11A and 11B with a small gap (proximity gap) from the wafers 13A and 13B, respectively, and are displaced in a rotational direction around an axis orthogonal to the reference plane. The inclination of 11B with respect to the reference plane can be adjusted. Alignment marks 12A and 12B are formed on the masks 11A and 11B, respectively.

  The mask alignment sensors 7A and 7B are arranged below the alignment marks 12A and 12B on the mask, respectively, so that the alignment marks 12A and 12B on the mask pass through the light-transmitting mark support portions of the reference masks 8A and 8B. 12B can be detected simultaneously with the reference marks 9A and 9B.

  Wafer alignment sensors 10A and 10B are attached to the sides of mask stages 6A and 6B, respectively, facing fine movement stages 5A and 5B. The wafer alignment sensors 10A and 10B can detect the positions of the reference marks 9A and 9B and the alignment marks 14A and 14B on the wafer.

  Beam sources 19A and 19B are arranged above the mask stages 6A and 6B, respectively. The beam sources 19A and 19B generate low energy electron beams for exposure, respectively, and enter the wafers 13A and 13B via the masks 11A and 11B. Further, when the movable part of coarse movement stage 4 is moved, the relative positional relationship between fine movement stage 5A and beam source 19A and the relative positional relationship between fine movement stage 5B and beam source 19B are always the same. As shown, fine movement stages 5A and 5B and beam sources 19A and 19B are arranged.

  Leveling sensors 15A and 15B are arranged beside mask stages 6A and 6B so as to face fine movement stages 5A and 5B, respectively. Further, three leveling sensors 16A are attached to the surface of the mask stage 6A facing the fine movement stage 5A (only one is shown in FIG. 1). Similarly, three leveling sensors 16B are attached to the mask stage 6B. The leveling sensors 15A and 16A can measure the distance to the wafer 13A. Similarly, the leveling sensors 15B and 16B can measure the distance to the wafer 13B. The tilt of the wafer 13A can be detected by measuring a plurality of locations on the wafer 13A while moving the movable portion of the coarse movement stage 4. If at least three of the leveling sensors 15A and 16A simultaneously measure the distance to the wafer 13A, the tilt of the wafer 13A can be detected without moving the movable part of the coarse movement stage 4.

  Similarly, leveling sensors 17A and 17B are arranged on the holding surfaces of fine movement stages 5A and 5B, respectively, and the inclination of masks 11A and 11B can be detected. By adjusting the inclination of the masks 11A and 11B and the wafers 13A and 13B based on the detection result of the inclination, both can be arranged so as to be parallel to the reference plane.

  When the movable part of the coarse movement stage 4 is moved, the relative positional relationship between the leveling sensor 15A and the fine movement stage 5A and the relative positional relationship between the leveling sensor 15B and the fine movement stage 5B are always the same. Thus, the mounting positions of the leveling sensors 15A and 15B are determined. Thus, when the coarse movement stage 4 is operated to detect the inclination of the wafer 13A on one fine movement stage 5A, the inclination of the wafer 13B on the other fine movement stage 5B can be detected at the same time.

  Similarly, in the wafer alignment sensors 10A and 10B, when the movable portion of the coarse movement stage 4 is moved, the relative positional relationship between the fine movement stage 5A and the wafer alignment sensor 10A and the fine movement stage 5B and the wafer alignment are aligned. The relative positional relationship with the sensor 10B is always the same.

  Next, the detailed structure of the reference masks 8A and 8B will be described with reference to FIG. Hereinafter, the structure of the reference mask 8A will be described. The reference mask 8B also has the same structure as the reference mask 8A.

  2A and 2C are a bottom view and a cross-sectional view of the reference mask 8A. For example, a light transmissive membrane formed of a silicon nitride film, a silicon carbide film, or the like is formed on a support substrate 81A formed of a silicon substrate. A part of the support substrate 81A is etched to form an opening. The membrane left in the opening constitutes the mark support portion 82A. An opening is formed in a predetermined region of the mark support portion 82A, and this opening constitutes the reference mark 9A. The reference mark 9A can be detected by forming an optical image.

  The dimension x12 of the reference mask 8A is, for example, about 10 mm × 10 mm, and the dimension x11 of the opening of the support substrate 81A is, for example, 3 mm × 3 mm. By forming the reference mark 9A on the mark support portion 82A, it is possible to transmit the alignment mark detection light on the mask through the mark support portion 81A, and the reference mark 9A is optically observed and its position is detected. Can be detected.

  2D and 2E show other examples of the configuration of the reference mask 8A. The configurations of the support substrate 81A such as a silicon substrate and the mark support portion 82A are the same as the configurations of the reference masks in FIGS. An opaque pattern formed on the mark support portion 82A constitutes the reference mark 9A.

  The reference mark 9 </ b> A has a function of reflecting the light for detecting the reference mark, or the edge thereof scattering the light for detecting the reference mark. The reference mark 9A can be detected by forming an optical image of reflected light or scattered light. When detecting the scattered light from the edge, the incident direction of the illumination light of the reference mark 9A and the measurement direction of the scattered light from the edge can be selected to be asymmetric with respect to the normal line of the mark support portion 82A.

  The reference mark 9A can be detected from the coarse movement stage 4 side (downward in FIG. 1) by the mask alignment sensor 7A shown in FIG. 1, and detected from the mask stage 6A side (upward in FIG. 1) by the wafer alignment sensor 10A. can do. The alignment mark 12A on the mask can be detected from below by the mask alignment sensor 7A via the light transmissive mark support portion 82A of the reference mask 8A.

  The mark support part itself may be formed of a material that does not transmit light, and an opening for transmitting light may be formed in a part of the mark support part. In this case, the alignment mark 12A on the mask is detected by the mask alignment sensor 7A through the opening formed in the mark support portion. In any case, the alignment mark 12A on the mask is detected by the mask alignment sensor 7A via the reference mask 8A.

  FIG. 3A shows a partial cross-sectional view of the mask 11A. The other mask 11B has the same structure as the mask 11A.

  A mask membrane 112 such as a silicon nitride film or a silicon carbide film is formed on a support substrate 111 such as a silicon substrate. The support substrate 111 in the region where the circuit pattern to be exposed and the alignment mark are arranged is removed by etching. Only the mask membrane 112 remains in the portion where the support substrate 111 has been removed. By forming an opening in the mask membrane 112, the mask mark 12A and the circuit pattern 112 are formed.

  FIG. 3B shows a partial cross-sectional view of the wafer 13A. The other wafer 13B has the same structure as the wafer 13A. A detectable projection pattern (or recess pattern) is formed on a semiconductor substrate 131 such as a silicon substrate by, for example, a metal film or the like, and this pattern constitutes the alignment mark 14A. A resist layer 132 is formed to cover the alignment mark 14A.

  FIG. 3C schematically shows a configuration when the mask alignment sensor 7A is a chromatic aberration double focus optical system. A configuration in which the alignment mark 12A formed on the mask membrane 112 of the mask 11A and the stencil type reference mark 9A formed on the mark support portion 82A of the reference mask 8A are detected by the chromatic aberration double focus optical system 21 is shown. The chromatic aberration bifocal optical system 21 has different focal lengths f (λ) depending on the wavelength of light, and shows different focal lengths for illumination light of two wavelengths. On the optical axis of the chromatic aberration double focus optical system 21, the alignment mark 12A on the mask membrane 112 and the reference mark 9A on the mark support portion 82A are arranged at different positions. The images of the alignment mark 12A and the reference mark 9A on the mask are formed on the same image plane 22 by the chromatic aberration double focus optical system 21.

  FIG. 3D schematically shows a configuration when the mask alignment sensor 7A is an edge scattered light oblique detection system. An alignment mark 12A is formed on the mask membrane 112. A membrane type reference mark 9A is formed on the mark support portion 82A of the reference mask 8A. The optical axis of the edge scattered light oblique detection system 31 is arranged obliquely with respect to the normal lines of the mask 11A and the reference mask 8A. The relative positions of the alignment mark 12A and the reference mark 9A on the mask with respect to the direction perpendicular to the virtual plane including the normal line between the mask 11A and the reference mask 8A and the optical axis of the edge scattered light oblique detection system 31 Is detected.

  An object plane 32 and an image plane 33 are set in a plane perpendicular to the optical axis of the edge scattered light oblique detection system 31. An alignment mark 12A and a reference mark 9A on the mask arranged in the vicinity of the object plane 32 are imaged on the image plane 33. When the edge scattered light oblique detection system is used, the detection direction is limited to one direction within the object surface 32. In order to detect the position in two directions in the plane, two edge scattered light oblique detection systems may be provided. Details of position detection using the edge scattered light oblique detection system are disclosed in Japanese Patent Laid-Open No. 10-242036.

  Next, with reference to FIGS. 4A to 4C, steps from the position detection of the wafer and the mask to the exposure will be described.

  As shown in FIG. 4A, masks 11A and 11B are held on mask stages 6A and 6B, respectively. Wafers 13A and 13B are held on the holding surfaces of fine movement stages 5A and 5B, respectively. The mask alignment sensor 7A simultaneously observes the reference mark 9A of the reference mask 8A and the alignment mark 12A of the mask 11A, and detects the positions of both. Similarly, the positions of the reference mark 9B and the alignment mark 12B are detected by the other mask alignment sensor 7B.

  As shown in FIG. 4B, the movable portion of the coarse movement stage 4 is moved so that the reference marks 9A and 9B are arranged in the field of view of the wafer alignment sensors 10A and 10B, respectively. The positional deviation in the X-axis direction between the alignment mark 12A on the mask and the reference mark 9A in the state of FIG. 4A, the X coordinate of the reference mark 9A detected by the wafer alignment sensor 10A, and the movement of the coarse movement stage 4 Length in the X-axis direction from the alignment mark 12A on the mask to the wafer alignment sensor 10A (for example, the origin in the screen) (the length of the X-direction baseline) BXA Is determined. Similarly, the positional deviation in the Y-axis direction between the alignment mark 12A on the mask and the reference mark 9A in the state of FIG. 4A, the Y coordinate of the reference mark 9A detected by the wafer alignment sensor 10A, and the coarse movement stage 4 is the length in the Y-axis direction (the length of the Y-direction baseline) from the alignment mark 12A on the mask to the wafer alignment sensor 10A (for example, the origin in the screen). It is determined.

  Similarly, with respect to the alignment mark 12B on the other mask and the wafer alignment sensor 10B, the length BXB of the X-direction baseline and the length of the Y-direction baseline are determined.

  As shown in FIG. 4C, the movable part of the coarse movement stage 4 is moved so that the alignment marks 14A and 14B on the wafer are arranged in the field of view of the wafer alignment sensors 10A and 10B, respectively. The position of the alignment mark 14A is detected by the wafer alignment sensor 10A. Further, the positions of a plurality of alignment marks on the wafer 13A are detected. Based on the detection result of the alignment mark and the amount of movement of the movable part of the coarse movement stage 4, the position information of the wafer 13A in the coordinate system fixed to the wafer alignment sensor 10A (for example, position information about the X-axis and Y-axis directions, and Z Position information regarding the rotation direction around an axis parallel to the axis). From these pieces of position information, position information of the dies on the wafer 13A (regions serving as units exposed by the step-and-repeat method) can be obtained.

  Relative position information between the mask 11A and the wafer 13A is obtained from the X-direction base line BXA, the Y-direction base line, and die position information. Based on this positional information, global alignment of each die can be performed. Similarly, position information necessary for global alignment can be obtained for the wafer 13B. At the time of global alignment, the two masks and the wafer can be aligned at the same time by independently moving the holding surfaces of the fine movement stages 5A and 5B. Each die on the wafer is sequentially exposed by the global alignment method. “Global alignment” is a method of performing alignment by calculating the position of a die by estimation calculation using wafer position information and moving the wafer based on the calculation result.

  In the first embodiment described above, the mask alignment sensor 7A simultaneously detects the reference mark 9A formed on the reference mask 8A and the alignment mark 12A on the mask 11A. The reference mask 8A can be formed to be light and small, and the transmittance of the mark support portion 82A shown in FIG. 3C can be set high. Therefore, simultaneous detection of the reference mark 9A and the alignment mark 12A on the mask is facilitated.

  The wafer alignment sensor 10A directly detects the reference mark 9A and the alignment mark 14A on the wafer without using the mask 11A. Therefore, the detection accuracy can be increased. Based on these highly accurate detection steps, the relative position between the wafer 13A and the mask 11A can be set with high accuracy. Similarly, the relative position between the other wafer 13B and the mask 11B can be set with high accuracy.

  In the method according to the first embodiment, since two wafers are processed in parallel, the throughput can be increased. In addition, since one coarse movement stage 4 is shared by the two fine movement stages 5A and 5B, the number of parts can be reduced and the apparatus can be downsized as compared with the case where two exposure apparatuses are prepared. It becomes possible.

  Next, a method for mounting two masks on the exposure apparatus shown in FIG. 1 will be described with reference to FIG.

  Masks 11A and 11B are placed on the holding surfaces of fine movement stages 5A and 5B, respectively. Masks 11A and 11B have a mask stage in which the distance between the centers in the X-axis direction is equal to the distance between the centers of wafer alignment sensors 10A and 10B, and the centers in the Y-axis direction coincide. 6A and 6B are preferably held. In order to hold the mask on the mask stage so as to satisfy this condition, an ideal position of the mask on the fine movement stage is determined in advance.

  The movable part of coarse movement stage 4 is moved, and the positions of a plurality of alignment marks on masks 11A and 11B are detected by wafer alignment sensors 10A and 10B, respectively. As a result, the positions of the masks 11A and 11B with respect to the X-axis direction and the Y-axis direction and the posture with respect to the rotation direction about the Z-axis are specified. A deviation from the ideal position of each of the masks 11A and 11B can be seen. The movable portion of the coarse movement stage 4 is moved so as to correct the displacement of the mask 11A, the mask 11A held on the holding surface of the fine movement stage 5A is raised, and is mounted on the mask stage 6A. The mask 11A is raised by, for example, lift pins provided on the holding surface.

  Next, the movable portion of the coarse movement stage 4 is moved so as to correct the displacement of the mask 11B, and the mask 11B held on the holding surface of the fine movement stage 5B is raised and mounted on the mask stage 6B. Thereby, the two masks 11A and 11B can be positioned at ideal positions and mounted on the mask stages 6A and 6B.

  Next, a second embodiment will be described. In the first embodiment, two fine movement stages 5A and 5B are provided with minute movement mechanisms in the X-axis direction and the Y-axis direction, and at least one of them is moved in the X-axis direction and the Y-axis direction. The relative positional relationship between the mask and the wafer was matched.

  In the second embodiment, in place of fine movement of the fine movement stages 5A and 5B, positional deviation correction in the X-axis direction and the Y-axis direction is performed by controlling the inclination of the exposure electron beam. For this reason, the fine movement stages 5A and 5B do not need to be provided with a fine driving mechanism in the X-axis direction and the Y-axis direction, and correct pitching, yawing, rolling, and wafer thickness variations of the coarse movement stage 4. For this purpose, only a minute rotation mechanism having a rotation axis in the direction parallel to the Z axis and a tilt adjustment mechanism (tilt correction mechanism) from the reference plane of the wafer need be provided. Even if the micro-drive mechanism in the X-axis direction and the Y-axis direction is omitted, the laser interferometer cannot be omitted because it is necessary to detect the orientation of the holding surface with respect to the micro-rotation direction and tilt.

  The time required for alignment can be shortened as compared with the case where the position shift correction in the X-axis direction and the Y-axis direction is performed by the fine movement stages 5A and 5B. This makes it possible to improve throughput.

  Next, an exposure apparatus according to the third embodiment will be described with reference to FIG. In the exposure apparatus of the first embodiment, the off-axis global alignment method is adopted. However, in the exposure apparatus described below, the die-by-die alignment method is adopted.

  6A is a plan view of the exposure apparatus according to the third embodiment, and FIG. 6B is a schematic cross-sectional view taken along one-dot chain line B6-B6 in FIG. 6A. The configurations of the reference base 3, coarse movement stage 4, fine movement stages 5A and 5B, mask stages 6A and 6B, leveling sensors 15A and 15B, and beam sources 19A and 19B are the same as those in the first embodiment shown in FIG. It is. In the plan view, four oblique detection optical devices 51A, 52A, 53A and 54A are arranged so as to surround the mask stage 6A. The oblique detection optical devices 51A, 52A, 53A and 54A are attached to the upper reference base 2 by three-axis stages 61A, 62A, 63A and 64A, respectively. The triaxial stages 61A, 62A, 63A, and 64A can move the oblique detection optical devices 51A, 52A, 53A, and 54A in the X axis direction, the Y axis direction, and the optical axis direction, respectively.

  The optical axes of the oblique detection optical devices 51A and 52A are tilted from the Z-axis direction in the negative and positive directions of the Y-axis, respectively. The optical axes of the oblique detection optical devices 53A and 54A are inclined from the Z-axis direction to the positive direction and the negative direction of the X-axis, respectively.

  Each oblique detection optical device 51A, 52A, 53A and 54A receives light scattered by the alignment mark on the mask and the edge of the alignment mark on the wafer, and forms an image of each alignment mark. The oblique detection optical devices 51A and 52A detect the position of the alignment mark in the X-axis direction, and the oblique detection optical devices 53A and 54A detect the position of the alignment mark in the Y-axis direction.

  Similarly, four oblique detection optical devices 51B, 52B, 53B and 54B are also arranged around the mask stage 6B. The oblique detection optical devices 51B, 52B, 53B and 54B are attached to the upper reference base 2 by three-axis stages 61B, 62B, 63B and 64B, respectively.

  Next, an exposure method using the exposure apparatus according to the third embodiment will be described. Wafers 13A and 13B are placed on the holding surfaces of fine movement stages 5A and 5B, respectively. The position information of the die of the wafer 13A is obtained by detecting the positions of the alignment marks on the wafer 13A by the four oblique detection optical devices 51A to 54A. At the same time, the position information of the die of the other wafer 13B is obtained. As a result, a positional shift that may occur during wafer loading is detected, and it is possible to perform rough alignment for each die prior to fine alignment performed for each die.

  The movable part of coarse movement stage 4 is moved, and the dies to be exposed on wafers 13A and 13B are moved directly below masks 11A and 11B, respectively. The relative position of the alignment mark on the wafer with respect to the alignment mark on the mask is detected by four oblique detection optical devices. From the detection result, the position in the X-axis direction and the Y-axis direction, the position in the rotation direction about the axis parallel to the Z-axis, and the relative expansion / contraction amount of the wafer with respect to the mask can be obtained. Based on these pieces of information, the holding surfaces of fine movement stages 5A and 5B are moved to align the mask and the wafer (this alignment is referred to as “fine alignment”). After the alignment is completed, exposure is performed.

  When performing die-by-die alignment, position detection and fine alignment are performed for each die, compared to the case of performing global alignment described in the first embodiment, which is disadvantageous in terms of throughput, but more accurate. Alignment can be performed.

  In the third embodiment, four oblique detection optical devices are arranged for each mask stage, but one of them may be omitted and three oblique detection optical devices may be arranged. When three oblique detection optical devices are provided, one of the position in the X-axis direction and the Y-axis direction, the position in the rotation direction about the axis parallel to the Z-axis, and the relative expansion / contraction amount of the wafer with respect to the mask is selected. Information cannot be obtained. Fine alignment is performed based on the obtained three pieces of information.

  For example, by omitting the oblique detection optical devices 54A and 53B disposed between the pair of mask stages 6A and 6B, the mask stages 6A and 6B can be brought closer to each other, and the size of the device can be reduced. .

  In die-by-die alignment, alignment is performed by detecting the alignment mark on the mask and the alignment mark on the wafer for each die. Therefore, fine movement mechanisms in the X-axis direction and the Y-axis direction are provided on the mask stage side. May be. At this time, a fine movement mechanism in the Z-axis direction, a tilt adjustment mechanism, and a rotation mechanism about an axis parallel to the Z-axis may be provided on the wafer stage side.

  Next, a method for mounting a wafer on the exposure apparatus according to the first to third embodiments will be described. With the holding surfaces of fine movement stages 5A and 5B arranged at the center of the movable range, wafers 13A and 13B are placed and fixed at predetermined positions on the holding surfaces of fine movement stages 5A and 5B, respectively. The position where the wafer is to be placed first is referred to as a “placement target position”. In the conventional exposure apparatus, when the position of the wafer is deviated from the placement target position, this deviation can be corrected by moving the movable part of the coarse movement stage.

  In the case of the above embodiment, when the two wafers 13A and 13B are displaced by the same amount in the same direction from the placement target position, the displacement is corrected by moving the movable portion of the coarse movement stage 4. be able to. However, when the direction and amount of deviation are different, that is, the relative positional deviation between the two wafers cannot be corrected by the coarse movement stage 4, but must be corrected by the fine movement stages 5A and 5B.

  Usually, the stroke of the fine movement stage used in the exposure apparatus is generally about 40 μm. For this reason, if the relative positional deviation amount of the two wafers is 40 μm or more, the deviation of the wafer from the placement target position cannot be corrected. In order to ensure the original function of the fine movement stage for finely moving the wafer when aligning the mask and the wafer, it is preferable to set the relative positional deviation at the time of placing the wafer to 20 μm or less. When focusing on one wafer, it is preferable to set the deviation from the mounting target position to 10 μm or less (generally, 1/4 times or less the stroke of the fine movement stage).

  Note that the deviation in the rotation direction when the wafer is placed can be corrected by providing a coarse rotation mechanism for each fine movement stage.

  Even when the relative displacement between the two masks is an amount that cannot be corrected by the fine movement stage, the correction by the fine movement stage and the correction by controlling the tilt (incident angle) of the electron beam are combined. In some cases, it can be corrected. In such a case, the exposure process can be continued without remounting the wafer.

  In the above embodiment, the two fine movement stages 5A and 5B are attached to the movable part of one coarse movement stage 4, but it is also possible to attach three or more fine movement stages.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

  The present invention can be applied to low energy electron beam exposure. In addition, X-ray proximity exposure can be applied. Further, the present invention can be applied to alignment of a processing object (wafer) in reduced projection exposure.

1 is a schematic view of an exposure apparatus according to a first embodiment. (A) and (C) are a bottom view and a sectional view of a stencil type reference mask, respectively, and (B) and (D) are a bottom view and a sectional view of a membrane type reference mask, respectively. (A) is a sectional view of a mask, (B) is a sectional view of a wafer, (C) is a schematic sectional view of a mask, a reference mask, and a chromatic aberration double focus optical system for observing the mask, D) is a schematic sectional view of a mask, a reference mask, and an oblique detection optical system for observing the mask. It is the schematic (the 1) of the principal part of the exposure apparatus for demonstrating the method of aligning with the exposure apparatus by a 1st Example. It is the schematic (the 2) of the principal part of the exposure apparatus for demonstrating the method of aligning with the exposure apparatus by a 1st Example. It is the schematic (the 3) of the principal part of the exposure apparatus for demonstrating the method of aligning with the exposure apparatus by a 1st Example. It is the schematic for demonstrating the method to mount | wear with the mask to the exposure apparatus by an Example. (A) and (B) are respectively a plan view and a cross-sectional view of an exposure apparatus according to the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lower reference base 2 Upper reference base 3 Reference base 4 Coarse movement stage 5A, 5B Fine movement stage 6A, 6B Mask stage 7A, 7B Mask alignment sensor 8A, 8B Reference mask 9A, 9B Reference mark 10A, 10B Wafer alignment sensor 11A , 11B Mask 12A, 12B, 14A, 14B Alignment mark 13A, 13B Wafer 15A, 15B, 16A, 16B, 17A, 17B Leveling sensor 19A, 19B Beam source 21 Chromatic aberration double focus optical system 22, 33 Image plane 31 Oblique detection Optical system 32 Object surfaces 51A to 54A, 51B to 54B Oblique detection optical devices 61A to 64A, 61B to 64B Triaxial stage 81A, 111 Support substrate 82A Mark support portion 112 Mask membrane 113 Circuit pattern 131 Semiconductor substrate 132 Strike layer

Claims (11)

A coarse movement stage that is attached to a reference base that defines a reference plane that serves as a reference for position, and that moves a movable portion in a direction parallel to the reference plane;
A plurality of fine movement stages each provided with a holding surface for holding a processing object, and capable of moving the holding surface in a direction parallel to the reference surface with respect to the movable portion of the coarse movement stage;
A beam source for irradiating the processing object held on the holding surface of the corresponding fine movement stage and irradiating an energy beam with each fine movement stage, and arranged on each of the fine movement stages and held on the holding surface of the corresponding fine movement stage An object alignment sensor for detecting the position of the processing object;
When the movable portion of the coarse movement stage is moved, the relative positional relationship between each fine movement stage and the corresponding object alignment sensor is always the same for all fine movement stages. An exposure apparatus in which an alignment sensor for an object is arranged. When the movable portion of the coarse movement stage is moved, the fine movement stage and the fine movement stage so that the relative positional relationship between each fine movement stage and the corresponding beam source is always the same for all fine movement stages. The exposure apparatus according to claim 1, wherein a beam source is arranged. Further, for each fine movement stage, a leveling sensor that is disposed at a position facing the holding surface of the corresponding fine movement stage and measures the distance to the processing object held on the holding surface is attached to the reference base. The leveling sensor is arranged so that when the coarse movement stage is moved, the relative positional relationship between each fine movement stage and the corresponding leveling sensor is always the same for all fine movement stages. The exposure apparatus according to claim 1 or 2, wherein The exposure according to any one of claims 1 to 3, further comprising a mask stage arranged for each fine movement stage and holding a mask with a minute gap from a processing object held on a holding surface of the corresponding fine movement stage. apparatus. Further, a mark support portion arranged for each fine movement stage, in which a region for transmitting light is defined at least in part, and a reference mask including a reference mark formed on the mark support portion;
5. A mask alignment sensor prepared for each fine movement stage and capable of detecting an alignment mark on a mask held on the corresponding mask stage through a corresponding reference mask and detecting a corresponding reference mark. The exposure apparatus described. A coarse movement stage that is attached to a reference base that defines a reference plane that serves as a reference for position, and that moves a movable portion in a direction parallel to the reference plane;
A plurality of fine movement stages attached to the movable portion of the coarse movement stage, each of the fine movement stages has a holding surface for holding a processing object, and the processing object held on the holding surface, The position of the object to be processed held in the holding surface in the direction parallel to the reference surface has a function of moving in a direction perpendicular to the reference surface and a function of adjusting the inclination with respect to the reference surface. A plurality of fine movement stages fixed to the movable part of the stage;
An electron beam source arranged for each fine movement stage and capable of irradiating an electron beam onto a processing object held on a holding surface of the corresponding fine movement stage and changing an incident angle of the electron beam to the processing object When,
An exposure apparatus that includes an object alignment sensor that is disposed for each fine movement stage and detects a position of a processing object held on a holding surface of the corresponding fine movement stage. (A) A processing object is held on each holding surface of each of a plurality of fine movement stages attached to a movable portion of a coarse movement stage that is movable in a direction parallel to a reference surface, and each of the processing objects corresponds. Placing it close to the mask;
(B) Using a mask alignment sensor that is arranged for each fine movement stage and moves in accordance with the movement of the movable part of the coarse movement stage, the movement of the movable part of the coarse movement stage that is arranged for each fine movement stage. Detecting a reference mark that moves along with the alignment mark on the corresponding mask;
(C) The movable portion of the coarse movement stage is moved, a corresponding reference mark is arranged at a position facing the object alignment sensor arranged for each fine movement stage, and the object alignment sensor Detecting the position of the corresponding reference mark;
(D) The movable part of the coarse movement stage is moved, and an alignment mark on the processing object held by the corresponding fine movement stage is arranged at a position facing the alignment sensor for the object, A step of detecting the position of the alignment mark on the object by the alignment sensor;
(E) Based on the position detection result in the step b, the movement amount and position detection result of the movable portion of the coarse movement stage in the step c, and the movement amount and position detection result of the movable portion of the coarse movement stage in the step d. And a step of obtaining relative position information between each of the masks and the object to be processed held on the holding surface of the corresponding fine movement stage. further,
(F) Based on the relative position information obtained in the step e, global alignment is performed between the mask and the processing object held on the holding surface of the corresponding fine movement stage, and the processing object is exposed through the mask. The alignment processing method according to claim 7, comprising a step of: Even if the step f moves the holding surfaces of two fine movement stages within the range of the stroke, the processing object held on the holding surfaces of the two fine movement stages and the corresponding masks 9. The alignment processing method according to claim 8, comprising a step of performing exposure by correcting a positional shift by changing an incident angle of an electron beam incident on a processing object when the positions cannot be adjusted simultaneously. Step f is
(F1) The position of the processing object held on the holding surface of the fine movement stage and the corresponding mask by moving the movable part of the coarse movement stage based on the relative position information acquired in the step e. A process of combining,
(F2) The processing object subjected to alignment is exposed by making an electron beam incident through a corresponding mask, and for other processing objects, the relative position information acquired in step e, and Based on the amount of movement of the movable part of the coarse movement stage in step f1, the amount of positional deviation between the object to be processed and the corresponding mask is calculated, and the incident angle of the electron beam incident on the object to be processed is changed. The alignment processing method according to claim 8, further comprising a step of performing exposure after correcting misalignment. Corresponding to the mask stage arranged for each fine movement stage by holding the processing object on the holding surface of each of the multiple fine movement stages attached to the movable part of the coarse movement stage movable in the direction parallel to the reference surface The mask is held close to the processing object to be detected, and the alignment mark on the corresponding processing object is detected by the object alignment sensor arranged for each fine movement stage, and the mask and the corresponding processing object are detected. A method of attaching a mask to a mask stage of an exposure apparatus that performs alignment with an object and exposes a processing object through the mask,
(A) a step of holding a mask on each holding surface of the fine movement stage;
(B) moving the movable part of the coarse movement stage so that the alignment mark on the mask held on the holding surface of the fine movement stage is arranged at a position detected by the corresponding alignment sensor for the object;
(C) For all the masks held on the holding surface of the fine movement stage, detecting the position of the alignment mark on the mask held on the holding surface of the corresponding fine movement stage by the alignment sensor for the object; ,
(D) Based on the detection result of the position of the alignment mark on the mask held on the holding surface of one fine movement stage, the coarse movement stage is arranged so that the mask is arranged at a position facing the corresponding mask stage. Moving the movable part and holding the mask on the corresponding mask stage;
(E) A mask mounting method including a step of repeating the step d for all masks.

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